CHARLES D. WINTERS / SCIENCE PHOTO LIBRARY CHARLES D. WINTERS / SCIENCE PHOTO LIBRARY
Acid-base titration. Demonstration of an acid-base titration using the indicator phenolphthalein. An alkaline solution is in the flask with a few drops of the indicator added to give a purple colour. Acid is slowly added from the burette above. When the acid has neutralised the alkali in the solution, the indicator turns colourless. The amount of acid needed to neutralise the alkali will allow the concentration of one of the solutions to be determined provided that the other's strength is already known.
Model release not required. Property release not required.